Air suspension control

ABSTRACT

Example illustrations are directed to a suspension system for a vehicle and methods. In some examples, a controller of a suspension system is configured to determine the vehicle is in a service environment, and to set a height precision mode for the suspension system based on the determination the vehicle is in the service environment. In some examples, the controller is configured to detect a suspension operating condition of the vehicle, and to change a setting associated with the suspension system based on the suspension operating condition. An example method comprises detecting, using a controller, a suspension operating condition of a suspension system of a vehicle. The method may further include changing, using the controller, a setting associated with the suspension system based upon the suspension operating condition.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 63/226,679, filed on Jul. 28, 2021, and U.S.Provisional Patent Application Ser. No. 63/240,689, filed on Sep. 3,2021, and the contents of each application is hereby expresslyincorporated by reference in their entireties.

INTRODUCTION

The present disclosure is directed to a vehicle suspension system, andmore particularly to a vehicle suspension system that allows foradjustments to a ride height of a vehicle.

SUMMARY

Some vehicle suspension systems allow manual or automatic adjustments tovehicle height. For example, a user may be allowed to select differentride heights, e.g., to modify vehicle capabilities for off-road use. Inanother example, a vehicle may have an automatic levelling system thatresponds to changes in vehicle loading to level the vehicle, e.g., inresponse to a heavy load being placed in a rear cargo area of thevehicle. Rough road surfaces may cause the vehicle to perform levellingevents excessively to the extent the vehicle attempts to respond torapid changes in wheel position. This can be noticed by vehicleoccupants as overactivity and unnecessary actuation by the levellingsystem. Accordingly, in some example illustrations herein a roadroughness metric or estimator dynamically estimates a roughness value,which may be used to widen acceptable control tolerances of the airsuspension system when the road is relatively rougher. On theserelatively rough surfaces, over-corrections by the levelling system maybe reduced or prevented entirely. Additionally, tolerances may bealtered in response to a determination that a road surface is relativelysmooth, allowing the levelling system to make levelling adjustments asappropriate.

Another problem for vehicles with automatic levelling systems ariseswhen suspension or other components are incorrectly installed orserviced. For example, if an incorrectly installed or serviced vehiclecomponent would cause a vehicle to lean, e.g., toward one side or cornerof the vehicle, the automatic levelling of the vehicle in response willnecessarily increase the weight applied by the wheels at that side orcorner to the ground surface, creating an asymmetry in the wheel weightsof the vehicle. The asymmetric corner weights negatively affect vehicledynamic behavior. Moreover, the level appearance of the vehicle may maskthe underlying condition to service or assembly personnel. Accordingly,in some example illustrations uneven corner weights may be addressed byemploying a control methodology for levelling vehicle suspension in amanner that facilitates identification of incorrect vehicle suspensioninstallation or setup, while responding appropriately during normalconditions or operation.

In at least some example illustrations, a suspension system for avehicle includes a controller configured to determine the vehicle is ina service environment. The controller may also be configured to set aheight precision mode for the suspension system based on thedetermination the vehicle is in the service environment.

In at least some example suspension systems, the height precision modeincludes at least a plurality of height precision modes having differentcorresponding control tolerances. Further, the controller may beconfigured to identify an optimal one of the plurality of heightprecision modes based on the suspension system operating condition, andto modify the suspension system to be in the determined height precisionmode. Additionally, setting the height precision mode to decrease thecontrol tolerance may, in these examples, disable an average axlecontrol leveling of the vehicle.

In at least some examples, the controller is further configured todetermine the vehicle is outside of the service environment to set aheight axle control mode. Further, the height axle control mode includesat least an average axle control methodology. A height adjustment of thesuspension may be based upon an average of two vehicle heightsdetermined at a single axle of the vehicle.

In at least some example suspension systems, the controller is furtherconfigured to determine the vehicle is outside of the serviceenvironment to set a height axle control mode. Additionally, the heightaxle control mode further includes an independent axle controlmethodology, wherein first and second height adjustments areindependently implemented at a first wheel of an axle of the vehicle anda second wheel of the axle.

In a subset of these examples, the controller is configured to implementthe independent axle control methodology in response to one of detectinga height error or detecting an incomplete height correction.

In at least some examples, a suspension system for a vehicle is providedthat includes a controller configured to detect a suspension operatingcondition of the vehicle. The controller may also be configured tochange a setting associated with the suspension system based on thesuspension operating condition.

In at least some example suspension systems, the suspension operatingcondition includes one of a ground surface angle, a vehicle steeringangle, a vehicle speed, a suspension correction condition, or an ambienttemperature.

In at least some examples, the setting associated with the suspensionsystem includes one of a height change limit, a vehicle speed limit, aheight change precision, an axle height adjustment independence level, aheight adjustment threshold, or a suspension activity.

In at least some example suspension systems, the suspension operatingcondition comprises a vehicle ground height. The setting associated withthe suspension system may comprise a vehicle speed limit. Additionally,the controller may be configured to implement the vehicle speed limit inresponse to the vehicle ground height being above a predeterminedvehicle height threshold.

In at least some examples, the suspension operating condition comprisesvehicle speed, and the setting associated with the suspension systemcomprises a vehicle height limit. Additionally, the controller may beconfigured to implement the vehicle height limit in response to thevehicle speed being above a predetermined vehicle speed threshold.

The suspension operating condition may, in at least some examples, beone of an individual wheel articulation above a predetermined relativearticulation threshold, an automatic levelling event, a drive modechange, or an operating environment of the vehicle. In these examples,the setting may comprise an axle height control methodology.

In at least some examples, the axle height control methodology includesat least an average axle control methodology. Additionally, a heightadjustment of the suspension may be based upon an average of two vehicleheights determined at a single axle of the vehicle. In at least a subsetof these examples, the axle height control methodology further includesan independent axle control methodology, in which the first and secondheight adjustments are independently implemented at a first wheel of anaxle of the vehicle and a second wheel of the axle.

In at least some example suspension systems, the controller isconfigured to implement the independent axle control methodology inresponse to one of (a) detecting the operating environment of thevehicle is a service environment, (b) detecting a height error, or (c)detecting an incomplete height correction.

In at least some examples, the controller is configured to implementheight changes at two different axles within an axle height differencelimit, such that a first height change is initiated at a first one ofthe two axles until the axle height difference limit is reached, and asecond height change is initiated at a second one of the two axles untilone of the height difference limit or an overall height change isreached. The second height change may, in these examples, be initiateduntil the height different limit is reached, wherein the controllerimplements a third height change at the first one of the two axles.

In at least some example suspension systems, the suspension operatingcondition includes an ambient temperature of the vehicle. Additionally,the controller may be configured to reduce a suspension activity inresponse to a first temperature detected above a predeterminedthreshold.

The controller may, in at least some examples, be configured to change asuspension activity between a plurality of discrete suspension activitycategories. Each of the discrete suspension activity categories, inthese examples, include one or more suspension operating parameteradjustments.

In at least some example suspension systems, the controller isconfigured to equalize an air pressure of a plurality of air springs ofa single axle after implementing a height change at the single axle,with the plurality of air springs being associated with opposite wheelsof the single axle.

In at least some examples, the controller is configured to change one ormore heights of the vehicle by changing an air pressure of one or moreair springs of the vehicle.

In at least some example illustrations, a method is provided comprisingdetecting, using a controller, a suspension operating condition of asuspension system of a vehicle. The method may further include changing,using the controller, a setting associated with the suspension systembased upon the suspension operating condition.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic illustration of a vehicle having a suspensionsystem that allows for adjustments to a vehicle ride height by way ofadjustable air springs, in accordance with an example approach;

FIG. 2 shows a schematic illustration of the vehicle of FIG. 1illustrating example pneumatic and electrical connections of thesuspension system, according to an example;

FIG. 3 shows a user interface for interacting with the suspension systemof FIGS. 1 and 2 , in accordance with an example;

FIG. 4 shows a user interface for interacting with the suspension systemof FIGS. 1 and 2 , in accordance with an example;

FIG. 5 shows a process flow diagram for a method of facilitatingmodifications of a suspension system of a vehicle, including estimatinga roughness of a surface being traversed by the vehicle, according to anexample;

FIG. 6 shows a process flow diagram for a method of facilitatingmodifications of a suspension system of a vehicle, including modifying aheight adjustment tolerance of the vehicle, according to an example;

FIG. 7 shows a process flow diagram for a method of altering suspensionsettings, according to an example;

FIG. 8 shows a correction strategy for suspension levelling correctionsof a vehicle, in accordance with an example approach;

FIG. 9 shows an example correction strategy for suspension levellingcorrections of a vehicle, in accordance with an example;

FIG. 10 shows a process flow diagram for a method of adjusting a rideheight of a suspension system for a vehicle;

FIG. 11 shows a process flow diagram for a method of equalizing airspring pressures in a suspension system for a vehicle, in accordancewith an example illustration;

FIG. 12 shows a control strategy for addressing over-corrections of anair suspension system of a vehicle, according to an example approach;

FIGS. 13A, 13B, and 13C each show strategies for reducing activity of asuspension levelling system, e.g., in a vehicle, in accordance withrespective example approaches;

FIG. 14 shows a process flow diagram of a method of adjusting rideheight of a suspension system of a vehicle, in accordance with anexample illustration;

FIG. 15 shows a schematic illustration of a vehicle having an airsuspension system that is over-constrained;

FIG. 16A shows a schematic illustration of a vehicle having an unequalweight distribution upon front and rear wheels of the vehicle, andcorresponding air suspension pressures;

FIG. 16B shows a process flow diagram of a method of adjusting rideheight of a suspension system of the vehicle of FIG. 16A, in accordancewith an example illustration;

FIG. 17A shows a chart of ride height selections versus vehicle speed inan “all-purpose” ride height control mode, according to an exampleapproach;

FIG. 17B shows a chart of ride height selections versus vehicle speed ina “conserve” ride height control mode, according to an example approach;

FIG. 17C shows a chart of ride height selections versus vehicle speed ina “sport” ride height control mode, according to an example approach;

FIG. 17D shows a chart of ride height selections versus vehicle speed ina “sport launch” ride height control mode, according to an exampleapproach;

FIG. 17E shows a chart of ride height selections versus vehicle speed inan “off-road auto/rock crawl” ride height control mode, according to anexample approach;

FIG. 17F shows a chart of ride height selections versus vehicle speed inan “off-road drift” ride height control mode, according to an exampleapproach;

FIG. 17G shows a chart of ride height selections versus vehicle speed inan “trailer towing” ride height control mode, according to an exampleapproach;

FIG. 18 shows a process flow diagram of a method of setting vehiclespeed limits in response to suspension system height inputs, inaccordance with an example illustration;

FIG. 19 shows a process flow diagram of a method of adjusting vehiclesuspension heights to facilitate ease of entry to a vehicle, inaccordance with an example illustration;

FIG. 20 shows a process flow diagram of a method of adjusting vehiclesuspension heights in conjunction with the ease of entry modeillustrated in FIG. 19 , in accordance with an example illustration;

FIG. 21 shows a process flow diagram of a method of adjusting vehiclesuspension heights to provide load levelling, in accordance with anexample illustration; and

FIG. 22 shows a process flow diagram of a method of facilitatingmodifications of a suspension system of a vehicle, including selectingand/or changing a control parameter.

DETAILED DESCRIPTION

As will be described further below, in at least some example approachesa roughness of a road, surface, trail, etc. may be approximated basedupon vertical displacement of the wheels away from an expected orneutral position over time, or as the vehicle traverses the road,surface, trail, etc. When driving on a very smooth surface, e.g., apaved road, vehicle wheels may tend to experience minimal verticalmovement. On rough surfaces, e.g., a gravel road, trail, or any off-roadenvironment, however, surface/road inputs will drive greater verticaldisplacement of the wheels away from their neutral position. It will beunderstood that reference to a “road” roughness or surface does notencompass only paved road surfaces, but also unpaved roads, gravel,dirt, or any off-road environment.

Example roughness metrics may be determined using a function oralgorithm that generally attempts to quantify how much road input thewheels experience over a distance, as a proxy for the roughness of thesurface. The quantified roughness may be used to influence operation ofthe suspension, e.g., by setting or altering control tolerances inresponse to changes in roughness. Example vehicles, suspension systems,and methods may thus be directed to determining a roughness metric of asurface being traversed by the vehicle based on ride height measurementsand setting a height adjustment parameter, e.g., a tolerance, for theair suspension system based on the roughness metric. As will bediscussed further below, in some example approaches an estimate ofsurface “flatness” may be used in conjunction with estimates ofroughness to facilitate changes to suspension adjustment parameters thatare appropriate for surface conditions. For example, estimates ofroughness and flatness may be used to desensitize a vehicle suspensionsystem such that fewer and/or less significant ride height changes aremade when surfaces being traversed by a vehicle are relatively rough ornon-flat. The vehicle and/or suspension system may have a controller ormodule configured to facilitate a modification of the suspension systembased on the determined height adjustment parameter. For example, heightadjustments may be facilitated by altering a tolerance associated withcontrolling one or more heights or displacements of a spring, e.g., anair spring of the vehicle. In some example approaches, a gain of acontroller may be changed to adjust a tolerance, e.g., to raise atolerance when a rough surface is detected, and/or a surface is inducingtwist in the vehicle suspension. As will be discussed further below, thevehicle may accordingly reduce or prohibit ride height changes, orchange methodology for ride height changes, during conditions whencorrective action may be difficult or likely to result in errors, e.g.,when vehicle wheels are rapidly being moved over time by a relativelyrough surface, or when relatively large amounts of suspension twist areinduced by non-flat surface.

In other example approaches, a vehicle suspension system may employdifferent control methodologies in an effort to allow visual diagnosisof incorrect installation or service of the vehicle. For example, aswill be described further below, when a vehicle is in a service ormanufacture setting, the vehicle may employ a relatively more precisecontrol methodology using independent control of the height at eachcorner/wheel/air spring of the vehicle. When the vehicle is not in suchservice/assembly conditions, a relatively lower precision controlmethodology may be used.

As also discussed further below, in some example approaches a vehicle,controller thereof, or method may be directed to detecting a suspensionoperating condition of the vehicle or operating environment, andchanging a setting associated with the suspension system based on thesuspension operating condition/environment. The suspension operatingconditions may include, merely as examples, a ground surface angle, avehicle steering angle, a vehicle speed, a suspension correctioncondition, or an ambient temperature, as will be discussed furtherbelow. Settings associated with the suspension system may include, forexample, a height change limit, a vehicle speed limit, a height changeprecision or tolerance, an axle height adjustment independence level, aheight adjustment threshold, or a suspension activity.

Turning now to FIGS. 1 and 2 , an example vehicle 100 having asuspension system 101 that allows for controlling vehicle ride height isillustrated and described in further detail, as may be used inconnection with various example illustrations herein. The vehicle 100may be a battery electric vehicle, e.g., with one or moremotor-generators driven by electrical power supplied by a battery pack(not shown). In FIG. 1 , pneumatic and electrical connections betweencomponents of the vehicle 100 discussed below are illustrated, inaccordance with an example approach. In FIG. 2 , vehicle 100 andsuspension system 101 are illustrated with the same pneumaticconnections illustrated in FIG. 1 , and more specific electricalconnections, e.g., electrical power, electrical signal, and electricalreturn connections are also illustrated. The vehicle 100 includes avehicle dynamics module 102 configured to control vehicle ride height,e.g., by way of one or more processors. The vehicle dynamics module 102may generally control one or more air springs 104 a, 104 b, 104 c, 104 d(collectively, 104). Generally, each of the air springs 104 may storepneumatic energy in a chamber between a corresponding wheel of thevehicle 100, and a body (not shown) of the vehicle 100. As noted in FIG.1 , the air springs 104 are each at a designated corner of the vehicle100, e.g., to function as a compliant element in the suspension of thevehicle 100. In addition to the compliance of the air springs 104, ashock or damper (not shown) may be provided at each vehicle wheel toabsorb mechanical energy imparted to the wheel by bumps or undulationsin a surface traversed by the vehicle 100. Moreover, the air springs 104may be configured to raise or lower a ride height of the vehicle 100.More specifically, each of the air springs 104 a, 104 b, 104 c, and 104d may raise or lower respective corner heights of the vehicle 100. Aswill be seen in further detail below, the vehicle dynamics module 102may implement changes in ride heights by way of the air springs 104,with each raising its associated corner height of vehicle 100. Thevehicle dynamics module 102 may, in some cases, automatically shiftbetween different ride heights in response to vehicle conditions. Inother cases, a user, e.g., driver of vehicle 100, may manually selectdifferent ride heights by way of a graphical user interface incommunication with the vehicle dynamics module 102. The vehicle 100 mayinclude one or more controllers, such as the vehicle dynamics module102. The vehicle dynamics module 102 and other controllers disclosedherein may comprise a processor and/or a memory. Example processors maybe a hardware processor, a software processor (e.g., a processoremulated using a virtual machine), or any combination thereof. In someembodiments, a processor and memory in combination may be referred to asa control circuitry of vehicle 100. In some embodiments, a processoralone may be referred to as control circuitry of vehicle 100. A memorymay comprise hardware elements for non-transitory storage of commands orinstructions, that, when executed by a processor, cause the processor tooperate the vehicle 100 in accordance with embodiments described aboveand below. For example, a memory may comprise a computer-readable ormachine-readable medium. Control circuitry may be communicativelyconnected to components of vehicle 100 via one or more wires, or viawireless connection.

The vehicle dynamics module 102 may be in electrical communication withan air compressor assembly 106, which generally controls system airpressure. More specifically, a storage volume of air may be containedwithin an air reservoir or tank 108. The air reservoir 108 may store airunder pressure, thereby maintaining a reserve of pneumatic energy thatmay assist the compressor 106 in raising ride height of the vehicle 100.A valve block assembly 110 actuated by the vehicle dynamics module 102may be positioned between the compressor 106 and air springs 104 and maybe configured to facilitate flow of air between components of thesuspension of the vehicle 100. For example, the valve block 110 maycontrol supply of air and/or pneumatic energy from the air reservoir 108to the air springs 104. The valve block assembly 110 may also facilitaterelease of air pressure from the air springs 104. Each of the airsprings 104 may be independently controlled, e.g., by way of the valveblock 110. For example, the valve block 110 may have a plurality ofvalves 111 (see FIG. 2 ) corresponding to each of the air springs 104and the tank 108. The compressor 106 may be controlled by the vehicledynamics module 102, e.g., by way of a compressor relay 114, and viatemperature sense and valve control inputs to the air compressorassembly 106. As will be detailed further below, corner heights ordisplacements of air springs 104 may be controlled on the basis of anycontrol parameters that are convenient. In one example approach, controlof the air springs 104 may be implemented using a displacement control,in which air may be added to/removed from air springs 104 on the basisof a target displacement of the air spring 104 and/or correspondingcorner height of the vehicle 100. For example, where a desireddisplacement of the air spring 104 is desired, an actual/measureddisplacement or corresponding corner height of vehicle 100 is measuredand compared with a target displacement/height, with air being addedto/removed from the air spring 104 accordingly. In another exampleapproach, the air springs 104 may be controlled using air mass control,in which air may be added to/removed from air springs 104 on the basisof a target amount or mass of air. For example, where a desireddisplacement of the air spring 104 is desired, a corresponding mass ofair that corresponds to the desired displacement and/or corner height ofthe vehicle 100 is determined, with air being added to/removed from theair spring 104 to reach the target air mass of the air spring 104. Instill another example, a displacement control and air mass control mayeach be selectively employed depending on conditions of a surface and/orthe vehicle 100, as will be discussed further below.

The vehicle 100 may also include ride height sensors 112 a, 112 b, 112c, and 112 d (collectively, 112), each configured to measure a verticaldisplacement between the corresponding wheel and the vehicle 100. Asuspension system of the vehicle 100 may generally automatically levelthe vehicle 100 and make changes to a ride height of the vehicle 100 byway of adjustments made to the air springs 104, e.g., in response to oneor more heights measured by the ride height sensors 112. Accordingly,when the vehicle 100 is carrying a relatively heavy load in a rear cargoarea, the rear ride height sensors 112 c, 112 d may detect that thevehicle height has been reduced. The vehicle 100 may, in response,increase an internal air pressure in the rear air springs 104 c, 104 dto level the vehicle 100.

In example illustrations herein, as will be elaborated further below,the vehicle 100 may alter a height adjustment parameter (e.g., atolerance setting of the automatic levelling system or anothersuspension parameter, or a change to a ride height) in response to adetection, e.g., by the vehicle 100, that a relatively rougher surfaceis being traversed. For example, the vehicle dynamics module 102 orother controller of vehicle 100 may be configured to increase a heightadjustment tolerance in response to an increase in the roughness metricof the road surface. Additionally, the vehicle 100 may decrease a heightadjustment tolerance in response to a detected decrease in the roughnessmetric of the road surface. As will be described further below, in someexample approaches a surface or roughness metric is based on a change incorner height error. As used herein, a corner height error is defined asa difference between expected ride height and the actual/measured rideheight, which may be determined by the sensors 112. Further, in someexamples the roughness metric employs a moving average of the cornerheight error over a given time window or period. While examples hereinare generally directed to altering tolerances for automatic levelling ofa suspension system of the vehicle 100, any other suspension parametersmay be adjusted in response to detected changes in roughness that areconvenient. Accordingly, to any extent a suspension parameter is capableof adjustment by the vehicle 100 and may be affected by variations inroughness of a surface being traversed by vehicle 100, the vehicle 100may adjust that parameter in response to detected variations inroughness. Merely by way of example, suspension damping settings such asdamper compliance/stiffness may be adjusted in response to variations inroughness, e.g., to increase compliance in response to an increase inroughness, and/or decrease compliance in response to a decrease inroughness.

A user may select various ride, suspension, or vehicle modes that mayinfluence performance of air suspension components. For example, asillustrated in FIGS. 3 and 4 , one or more user interfaces may beprovided for generally selecting a drive mode. The user interface 300 ofFIG. 3 and the user interface 400 of FIG. 4 may each be screens or menusprovided to a driver or other vehicle occupant, e.g., by way of a touchscreen. As shown in FIG. 3 , vehicle 100 is represented with a rideheight with respect to a ground surface 302. Similarly, the vehicle 100is represented in FIG. 4 with a ride height with respect to anotherground surface 402. The user interfaces 300, 400 may be in communicationwith vehicle dynamics module 102 to effect changes to the vehicle 100 orcomponents of the suspension of the vehicle 100. Merely by way ofexample, the various drive modes may affect the air suspension rideheight, e.g., by raising or lowering the vehicle 100, by alteringcompliance of the air springs 104 or dampers/shocks of the vehicle 100,etc. As illustrated in FIG. 3 , the vehicle 100 includes an all-purposemode, a sport mode, an off-road mode, a towing mode, and a conserve(electrical power) mode, each of which are displayed for selection inthe user interface 300. Upon selection of one of the modes in userinterface 300, a variety of sub-modes may be displayed. For example,upon selection of the off-road mode in user interface 300, asillustrated in FIG. 4 an automatic sub-mode, a rock crawl sub-mode, arally sub-mode, and a drift sub-mode may be displayed for selection inuser interface 400. One or more suspension or vehicle parameters may bedisplayed in connection with the modes and sub-modes included in theuser interfaces 300, 400. Merely as one example, different ride heightsmay be implemented in the vehicle modes and sub-modes, as will bediscussed further below. Additionally, as will also be described furtherbelow, a plurality of ride heights may be available within each of themodes and/or sub-modes which, as will be described further below, may betailored to desired performance traits of vehicle 100 for each of thegiven modes or sub-modes.

Turning now to FIG. 5 , an example process 500 for determining aroughness metric is illustrated and described in further detail. Theprocess 500 may generally be employed when the vehicle is moving, and assuch process 500, e.g., using the vehicle dynamics module 102, mayconfirm or query the vehicle 100 is in motion before employing process500 to determine a roughness metric. It should be noted that,alternatively, a previously determined roughness may be stored in anon-volatile memory of the vehicle, which may be used as the initialvalue of the estimator if it has not had any chance to calculate beforethe suspension is required to operate. This may be useful, e.g., forsituations in which the vehicle is parked upon a rough surface, so thatroughness is considered upon subsequent use of the vehicle, avoiding thevehicle suspension seeming overactive due to the rough surface. As aninput to process 500, corner height error(s) of one or more wheels ofthe vehicle 100 may be determined. In the example process 500,measurements are made based upon signals received from the four sensors112, each of which are positioned at a respective wheel of the vehicle100. Other numbers of sensors and wheels are possible in other exampleapproaches. Generally, corner height error(s) may be determined basedupon a difference between an expected or target height and an actualheight, e.g., as measured by ride height sensor(s) 112. Expected ortarget height may be determined in any manner that is convenient. Merelyby way of example, the target may be a desired ride height, e.g., 11.5″for an off-road mode of the vehicle 100, or a target corner height ofone or more air springs 104. A target height of a particular corner orlocation of the vehicle, e.g., where an air spring 104 is positioned,may vary dynamically as the vehicle moves. As such, a target height maybe adjusted to account for factors such as acceleration, deceleration,cornering, pitch, roll, and the like. In an example, the sensors 112 aredisplacement sensors that measure a displacement of the wheel from thevehicle 100, although in other examples a wheel accelerometer or thelike may be used.

At block 505 of process 500, the vehicle dynamics module 102 may convertthe corner height error to a delta or change in the corner height errormeasurement over a given time period. Initially, it should be understoodthat the vehicle dynamics module 102 may generally always have somenon-zero amount of height error which causes a DC-offset. As describedin further detail below, DC-offset generally refers to a physical offseterror in measurement, and can result from multiple sources, e.g., a bentsensor arm, an asymmetrically loaded vehicle, etc. To prevent thisDC-offset from being counted as road/surface input, process 500 mayremove the DC-offset from the corner height error measurements. Further,at block 505 it may also be desired to remove the effects of pitch orroll of the vehicle or other generally constant inputs to the suspensionthat are not caused by roughness. For example, where vehicle 100 isleaning to the passenger side while traversing a left turn, cornerheight errors may be present as a result of the lean of the vehicle, butthis effect is not caused by roughness. By comparison, where the vehicle100 is traversing a rough surface, corner height errors at the wheel(s)of the vehicle 100 may be rapidly changing as the wheel is jostled upand down. Accordingly, process 500 may convert the input corner heighterror to a delta or change in the corner height errors over time. Indoing so, the vehicle dynamics module 102 may generally remove morestatic effects caused by non-road roughness effects. Accordingly, aresult of block 505 may be a “corner surface input” at each air spring104 and/or wheel.

Proceeding to block 510, process 500 may determine a road or surfaceinput magnitude, e.g., by summing the absolute value of the cornersurface inputs determined at block 505. Accordingly, process 500 isagnostic regarding whether the surface/road inputs are positive ornegative (i.e., whether the rough surface is driving the wheelsup/down), and the surface input is simplified by determining theabsolute value of the changes in the individual corner height errors,and adding them together. Process 500 may then proceed to block 515.

At block 515, a speed dependent moving average filter may be applied tothe input surface input magnitude. Generally, instantaneous measurementof surface input magnitude may be a very noisy signal. Roughness of aroad surface, for example, may be obtained by applying a speed-dependentmoving average filter in an effort to normalize measurements for alength of road. For example, a filter time constant may be scaled withvehicle speed to achieve different behaviors at low speeds versus highspeeds. For example, at relatively lower speeds a smaller time constantmay be used, as it is desirable at low speeds for the roughness estimateto emphasize terrain that vehicle 100 has immediately traversed. Inother words, it may be desirable to interpret single events such as acurb impact or rock crawl as a relatively rough surface and reduce theextent to which levelling events might occur. This smaller time constantmay be useful for rock crawling or parking on top of a curb in a busyparking lot, merely by way of example. By contrast, a relatively largertime constant may be used at higher speeds, as the roughness estimatemay tend to be less noisy but more closely reflective of the generalroughness of the road surface (as opposed to discrete low-speed eventsor inputs, e.g., that may be typical of rock crawling). The relativelygreater time constant may be useful in reducing the effect of a singleinput at relatively higher speed, which may be less meaningful when thesurface is otherwise relatively smooth, and as a result it may be moredesirable for levelling events to proceed at such higher speeds. Anyfilter device or filtering methodology may be employed. In an example, a1st-order low-pass infinite impulse response (IIR) filter may beemployed, thereby outputting an exponentially weighted moving averagefilter. After block 515, process 500 may have a surface input magnitudeover a previous time window.

Proceeding to block 520, process 500 may apply a speed dependent gaindetermination to determine a final estimate of roughness, e.g., as apercentage. A gain of this determination may be speed-dependent, with asimilar rationale as the filter time constant of block 515. Accordingly,at a lower speed a relatively larger gain may be employed, while asmaller gain may be employed at a higher speed. In this manner,individual wheel displacements for lower speed events, e.g., likedriving up on a curb, are treated as a very rough road. In a furtherexample, a 40 millimeter (mm) displacement on one wheel may be observedat a vehicle speed of 20 kilometers/hour, which is treated as a veryrough road from the perspective of the ride height controller, i.e.,vehicle dynamics module 102. By comparison, at higher speeds arelatively smaller gain may be applied, as it may be desirable for theroughness metric to capture larger wheel displacement events but ignoresmaller events that are frequently seen while driving at high speedseven on relatively smooth surfaces. Process 500 may terminate, upondetermination of the roughness metric.

In some example illustrations, the vehicle 100 may be configured toselect various modes in response to detected conditions. In someexamples, vehicle 100 selects a height precision mode that facilitateschanging (a) a control tolerance associated with ride height changesand/or (b) a height axle control mode associated with a methodology usedto control ride height changes. For example, a height precision mode maybe changed to increase or decrease a precision with which ride heightchanges are made. A height precision mode may be selected from aplurality of height modes. Example height modes may include heightprecision modes, e.g., a nominal precision mode as well as a serviceprecision mode, in which changes to ride height are made with a greaterprecision and/or smaller control tolerance than the nominal precisionmode. Alternatively or in addition, height modes may include a pluralityof height axle control modes may be employed by the vehicle 100 inresponse to detected conditions. In examples herein, height axle controlmodes may include an average axle control methodology, in which a heightadjustment of the suspension is based upon an average of two vehicleheights determined at a single axle of the vehicle. Alternatively, inother situations the vehicle 100 may employ an independent axle controlmethodology, in which first and second height adjustments areindependently implemented at a first wheel of an axle of the vehicle anda second wheel of the axle. The axle control modes may be selected bythe vehicle 100 in response to detection of a service/manufacturingenvironment or other detected conditions, as will be discussed furtherbelow.

Example roughness metrics such as described above and illustrated inFIG. 5 generally do not change in value when a vehicle is stationary. Ifa vehicle stops and is turned off relatively quickly after pulling intoa driveway, the progression of the vehicle over a curb into the drivewayand almost-immediate stop following thereafter may cause the vehicle tobelieve it is parked on a “rough” surface when restarted. To correct forthis potential problem and facilitate appropriate changes to suspensionheight adjustment parameters, it may be useful to consider a “flatness”of a surface being traversed by a vehicle.

As used herein, “flatness” is refers as a lack of twist betweendifferent axles of a vehicle (e.g., between front and rear axles of avehicle). Accordingly, a surface upon which a vehicle rests may beconsidered perfectly “flat” if left/right displacements of front andrear axles are identical, i.e., the vehicle is “leaning” in the samedirection by the same amounts at both front and rear axles (or whenthere is zero lean at both axles). By comparison, a surface havingundulation(s) between front and rear axles causing the front vehiclesuspension to “lean” toward one side and the rear vehicle suspension tolean toward the opposite side is inducing “twist” in the vehicle, andthe surface is relatively less “flat” relative to the vehicle.Accordingly, in some example approaches a suspension system, vehicle, orassociated method may determine an amount of twist of the suspensionsystem, and determine a height adjustment parameter based on the twist.In at least some examples, twist may be used in combination with othermetrics, e.g., roughness, in determining a height adjustment parameter.Example illustrations for determining twist may include, as describedfurther below, determining a difference between a first lateraldisplacement difference of a front axle of the vehicle and a secondlateral displacement difference of a rear axle of the vehicle.

If a vehicle is on a surface causing twist in the suspension between thefront and rear axles/wheels, difficulties for the vehicle suspensionheight adjustments may result, particularly if the average axle controlmethodology mentioned above is being employed. More specifically, ifchanges in height are being controlled on the basis of an averagedisplacement of both air springs 104 at opposite sides of a single axlewhile the vehicle is leaning in opposite directions at the front/rearaxles, one side of the vehicle will tend to overshoot a ride heighttarget while the opposite side of the vehicle will tend to undershootthe ride height target. Accordingly, in some examples an independentcontrol methodology (i.e., each of the four wheels/air springs beingcontrolled independently) may be employed in response to a determinationthat the vehicle is on a relatively non-flat surface or the vehiclesuspension is undergoing at least a threshold amount of twist.Additionally, height changes may be restricted when the vehicle is onsurfaces inducing a threshold amount of twist in the vehicle suspension.It should be noted that measurements of flatness generally do not dependon dynamic movements of the vehicle and/or suspension, and as such donot lose relevance when a vehicle is stationary. By comparison, metricsof roughness may be less relevant when the vehicle is stationary as theyare determined based upon movements of the suspension/vehicle over timeor as the vehicle traverses a surface. As such, flatness measurementsmay provide useful information for a vehicle suspension system indetermining whether/when to reduce height change corrections,particularly at very low speeds or when the vehicle is stationary.

In an example, twist may be defined as a lack of flatness, and may bequantified by a difference between lateral or side-to-side displacementdifferences of two axles of a vehicle. Twist in a suspension may bebased upon a difference between (1) a first lateral displacementdifference of a front axle of the vehicle and (2) a second lateraldisplacement difference of a rear axle of the vehicle. In one example,this is calculated by:

(FL Displacement−FR Displacement)−(RL Displacement−RRDisplacement)=twist

where:

-   -   FL Displacement=displacement of the front-left air spring;    -   FR Displacement=displacement of the front-right air spring;    -   RL Displacement=displacement of the rear-left air spring; and    -   RR Displacement=displacement of the front-left air spring.        In other words, a difference in displacement between the        front-left and front-right air spring may be compared with a        difference in displacement between the rear-left and rear-right        air spring to determine twist. Where both front and rear axles        of the vehicle are leaning or rolled in the same        direction/amount (or are both level), twist will generally be        zero and the underlying surface may be thought of as being        “flat.” The above calculation provides a measure of vehicle        twist or diagonal loading. In an example, filtered signals for        each of the displacement measurements may be employed.

As will be described further below, the above measurement of flatness ortwist may be used in the context of vehicle 100 in at least several waysdescribed herein. First, height change requests may be rejected if thesurface is inducing certain amount of twist in the vehicle (or, putanother way, if the surface is non-flat to a certain degree).Additionally, vehicle 100 may use independent axle control methodologies(instead of average control) in response to a determined flatnessmetric. More specifically, if a surface is uneven, average axle controlcan lead to asymmetry of the vehicle upon driving away, as noted above.Further, vehicle 100 may determine a de-sensitization factor to beapplied to avoid or reduce the effect of ride height changes orlevelling events in response to a determined flatness metric.

In at least some example illustrations, vehicle 100 may determinesurface conditions based upon a flatness of the surface and a roughnessmetric, with height adjustment parameters being determined or adjustedin view of one or both of these factors. As noted above, flatness ortwist may be determined based upon static displacement measurements ofthe air springs 104, and as a result may provide useful informationwhile the vehicle 100 is stopped or at very low speeds. By comparison,roughness metrics as described above are determined based upon movementsof air springs 104 and/or other components of the vehicle 100 over time.Accordingly, in some example approaches, flatness and roughness areemphasized or de-emphasized based upon a speed of the vehicle 100. Forexample, roughness metrics may be relied upon to a greater degree (orexclusive of any consideration of flatness/twist) while vehicle 100 ismoving, with flatness/twist being relied upon to a greater degree (orexclusive of any consideration of roughness) when the vehicle 100 isstationary or at very low speeds, e.g., below 5 miles per hour (mph).Accordingly, in some example approaches a height adjustment parametermay initially be determined based on roughness, e.g., when the vehicleis in motion, with a subsequent height adjustment parameter beingdetermined based on twist, e.g., when vehicle speed drops to zero orbelow a speed threshold. Further, context switching may be used todetermine de-sensitisation factors to use with respect to a suspensionheight adjustment parameter. For example, if heights are known to beaccurate when a speed of vehicle 100 is above zero, de-sensitizations(e.g., to reduce interventions for height change corrections) may beapplied when the vehicle is stopped/static. On the other hand, if heightmeasurements are known to be less accurate while the vehicle 100 ismoving (i.e., vehicle speed is above zero), de-sensitization may beapplied based (only) on the determined flatness/twist.

Referring now to FIG. 6 , an example process 600 for determining aheight adjustment parameter, e.g., to adjust a tolerance of a vehiclesuspension for vehicle 100, is illustrated and described in furtherdetail. The height adjustment parameter may be used to facilitatemodification(s) of the suspension. Process 600 may begin at block 605,where surface conditions may be determined. Surface conditions mayinclude roughness (e.g., as set forth above by a roughness metric)and/or flatness characteristics (e.g., as set forth above by suspensiontwist). For example, upon detection that the vehicle 100 is in motion orturned on a controller, e.g., vehicle dynamics module 102, may determinea roughness metric of a surface being traversed by the vehicle 100 basedon ride height measurements, and/or a measurement of suspension twist.In an example, block 605 employs process 500 to determine the roughnessmetric, and measurements of suspension twist set forth above. Process600 may then proceed to block 610.

At block 610, process 600 queries whether a change in the surfaceconditions has taken place, e.g., based on the roughness metric and/orsuspension twist determined at block 605. In some examples, the query atblock 610 obtains a positive result only when at least one of theroughness metric or twist changes at least by a threshold amount orpercentage. Accordingly, the vehicle 100 can be prevented from makingchanges to suspension settings or ride height adjustment tolerances inresponse to small variations in terrain. Where block 610 obtains apositive result, process 600 may proceed to block 615, where a heightadjustment parameter, e.g., a height adjustment tolerance, may bemodified in accordance with the change in surface conditions.Accordingly, subsequent adjustments in ride height, e.g., by way ofadjustments to the air springs 104, may be affected. Alternatively, ifblock 610 obtains a negative result, process 600 proceeds back to block605. Accordingly, process 600 generally may continuously monitor thesurface conditions during operation of the vehicle 100.

Example roughness metrics, e.g., as determined using processes 500and/or 600, may be used to scale or adjust a height adjustment of thevehicle 100, e.g., a height adjustment tolerance of a levelling featureof the vehicle 100. Moreover, the tolerance adjustment may be performedin accordance with performance desires or expectations for the vehicle100. Merely as one example, to the extent the vehicle 100 is designedfor off-road or other non-road surfaces that are expected to be rough,the vehicle 100 may adjust tolerances more significantly. Generally,where a roughness metric is relatively greater, an extent and/or afrequency with which height adjustments are made to the vehiclesuspension may be reduced in comparison to relatively smoother roads orsmaller roughness metrics. Furthermore, to the extent a vehicle occupantor driver requests a change to the suspension, the roughness metric maybe used to reduce the extent of or pause entirely the requestedadjustments of suspension components. Merely as one example, whenvehicle 100 determines that roughness is below a predetermined threshold(i.e., indicating a relatively smooth ground surface), a relativelytighter height adjustment tolerance of 2 millimeters may be used forcontrol of vehicle ride height, while a relatively greater heightadjustment tolerance of 5 millimeters may be employed when the vehicle100 determines that the ground surface being traversed by the vehicle100 is above the predetermined threshold (i.e., indicating a relativelyrougher ground surface).

Modifications to suspension system 101 of vehicle 100 may be facilitatedby, for example, changing tolerances, control parameters ormethodologies of control as described further in the example processesor systems herein. Merely by way of example, modifications may befacilitated by one or more controllers, electronic control units (ECUs),or the like of vehicle 100 sending instructions to control variousaspects of the suspension system 101. For example, vehicle dynamicsmodule 102 may send software instructions to adjust values or types ofcontrol targets such as air mass, displacement, pressure, or othermechanical aspects of the air springs 104 and/or other components ofsuspension system 101. Facilitating modifications to suspension system101 of vehicle 100 may be performed in any manner that is convenient. Inan example, facilitating modifications to suspension system 101 ofvehicle 100 may be performed by implementing a height change parameter,e.g., to alter a tolerance associated with height changes, such as byadjusting a gain of a controller. In another example, facilitatingmodifications to suspension system 101 of vehicle 100 may be performedby altering a height axle control methodology or mode of the suspensionsystem 101, e.g., by switching from an average axle control methodologyto an independent axle control methodology, or vice versa. In stillanother example, facilitating modifications to suspension system 101 maybe performed by changing a control parameter for a height change, e.g.,changing from a displacement control to an air mass control, or viceversa.

Example roughness metrics as determined herein may provide benefitsbeyond load levelling aspects of a vehicle suspension system. Forexample, it may be beneficial to record or store roughness observed by agiven vehicle over time. Furthermore, to the extent the roughness metricevidences an outlier event or conditions of a vehicle, the metric may bebroadcast from the vehicle to provide a notification of the vehicleconditions. Additionally, as noted above other vehicle systems mayemploy the roughness metric, e.g., an adaptive damping controller of thevehicle, which may alter damping characteristics of the vehiclesuspension.

As noted above, in some example approaches vehicle 100 may be configuredto facilitate identification of incorrect vehicle or suspensioninstallation or setup in certain environments. In an example, acontroller such as the vehicle dynamics module 102 is configured todetermine the vehicle is in a service environment and set a heightprecision mode for the suspension system based on the determination thevehicle is in the service environment. The controller may also beconfigured to identify an optimal one of the plurality of heightprecision modes based on the suspension system operatingcondition/environment, e.g., detecting that the vehicle is in a serviceenvironment, and to modify the suspension system to be in the determinedheight precision mode. In examples herein, a service environment mayinclude a location for service such as a manufacturing facility orvehicle assembly facility, or a vehicle dealership or service station.The service environment may be detected, for example, by the use of anotification provided by service personnel to the vehicle 100 orcontroller thereof, e.g., by setting a flag recognized by the vehicledynamics module 102 to indicate that the vehicle 100 is in a serviceenvironment. In another example, a proximity of a sensor associated withservice environments may be detected by the vehicle automatically. Inanother example, GPS coordinates of the vehicle may be matched to aknown service location associated with the manufacturer of the vehicle.Accordingly, in these examples the vehicle 100 may be notified of theservice environment automatically. As examples herein are generallydirected to identification and correction of suspension systemadjustments, in at least some examples service environments may beidentified to the extent they are capable of performing suspensionsystem adjustments, e.g., they have appropriate tools, trainedpersonnel, etc. to correct problems or issues of the suspension systemof the vehicle 100 or components thereof.

It should be noted that a detection of a service environment need not beimmediately implemented for making adjustments to vehicle suspension.For example, the vehicle may implement the changed adjustment when thevehicle is being serviced and not merely sitting in the parking lot,e.g., when a customer initially arrives. In an example, servicepersonnel may place the vehicle in a service mode, or an ECU orcontroller of the vehicle 100 may detect that the vehicle is within athreshold proximity to a service machine (e.g., lift, service computer,etc.) to cause the suspension system 101 of the vehicle to be adjusted.In another example, the vehicle 100 may detect a proximity to a servicecenter, dealership, or the like, and in response to the detection makeavailable to the driver or service personnel a service mode of thevehicle 100. In other examples, the vehicle 100 may implement changesregardless whether the vehicle 100 is being serviced. In this manner, ifa vehicle 100 is brought to a service environment, e.g., at adealership, for some other reason, the vehicle may automaticallyinitiate the adjustment to make the underlying issue, e.g., suspensioncomponent out of specification, more apparent in the presence of servicepersonnel who are trained to notice that there is a problem and/or tocorrect it.

Referring now to FIG. 7 , an example process 700 for altering suspensionsettings is illustrated and described in further detail. At block 705,process 700 queries whether a height change is required. If a heightchange is not required, process 700 may proceed back to block 705,thereby monitoring for any required height change. Where a height changeis required, process 700 proceeds to block 710.

At block 710, process 700 queries whether vehicle 100 is in anenvironment requiring high precision for levelling adjustments, e.g., aservice environment or a manufacturing environment. As noted above, inone example, the vehicle 100 may set a service or manufacture flag thatpersists for a period of time, e.g., 24 hours, upon activation bymanufacturing or service personnel, detection by the vehicle 100 that itis in/near a service environment, etc., or otherwise in any mannerdescribed herein. If block 710 determines that the vehicle is in aservice/manufacturing environment, process 700 may then proceed to block715.

At block 715, a high-precision mode of the air suspension levellingsystem may be enacted, relying upon an independent control of each ofthe air springs 104. In this manner, levelling adjustments may be madegenerally with a relatively greater amount of precision, facilitatingidentification of issues caused by incorrectly installed components. Asone example, where a suspension bushing is over-torqued duringinstallation or service, a levelling event of the vehicle and resultingrelative increase of vehicle corner weight(s) at associated airspring(s) 104 and/or wheel(s) of the vehicle may evidence the issue. Byincreasing precision of the levelling control system in thisenvironment, the vehicle 100 may be more aggressive with levellingadjustments, thereby exacerbating any resulting corner weightdifferences caused by the levelling and underlying suspension condition.Additionally, process 700 may disable average axle control levelling atblock 715, such that each of the air springs 104 are independentlyadjusted for height. In this manner, corner weight differences from sideto side in the vehicle are also more easily observed, in addition tothose observed between front/rear wheel corner weights. The increasedaccuracy of the high-precision mode and the use of independent controlfor each air spring 104 may help identify the source of the underlyingproblem, e.g., by isolating a particular wheel/air spring 104 where acorner weight of the vehicle 100 is particularly heavy/light in relationto the other corner weights.

In at least some examples herein, the vehicle 100 includes a pluralityof height precision modes having different corresponding controltolerances. For example, in addition to the high-precision mode of theair suspension levelling system, a low-precision (relative to thehigh-precision mode) mode may be available for othersituations/settings, as will be discussed further below.

Where block 710 determines that the vehicle is not in a service ormanufacturing environment (or, for that matter, other environment wherehigh-precision control of levelling is unnecessary), process 700 mayproceed to blocks 720-730, in which a reduced precision controlmethodology for height changes is used. For example, a smaller precisioncontrol methodology (e.g., to a height adjustment tolerance of 5millimeters, instead of a higher-precision height adjustment toleranceof 2 millimeters) may prevent excessive automatic levelling of thevehicle 100.

At block 720, process 700 queries whether the required height changedetermined at block 705 is the result of an automatic levelling event(i.e., an automatic correction of the vehicle 100 in response to loadingthe rear or side of the vehicle, for example) or a high-articulationevent. A high-articulation event may be defined as a movement orarticulation of a single wheel, i.e., an individual wheel articulation,that exceeds a predetermined relative articulation threshold. Arelatively high-articulation event may be indicative of (i.e., where thesuspension travel exceeds a predetermined minimum or predeterminedrelative articulation threshold), merely as examples, off-road operationor other extreme inputs to the vehicle suspension. In either case, itmay be desired to employ an independent control of each of the airsprings 104 and/or associated wheels. More specifically, conditionscreating a need for an automatic levelling event generally cannot beassumed to apply equally to both driver and passenger sides of thevehicle 100, e.g., the vehicle has been heavily loaded on the driver'sside of the rear cargo area, and as such it is desired to ensure thevehicle 100 is level from side to side. Additionally, ahigh-articulation event may also warrant independent control of the airsprings 104 and/or wheels. Where block 720 determines that one of alevelling event or high-articulation event is present, process 700 mayproceed to block 725. At block 725, the vehicle 100 employs a normalprecision, independent control methodology, in which the controltolerances of the adjustments are within normal parameters. In anexample, the relatively lower precision of the normal-precision controlmethodology (e.g., to within 5 millimeters of the target position, asopposed to within 2 millimeters of the target position forhigh-precision control) is configured to prevent overcorrection by thevehicle 100 and/or suspension system when it may not be needed. Itshould be noted that an average axle control (e.g., as described aboveat block 715) may be disabled at block 725 in response to the decreasein the control tolerance, such that the vehicle 100 employs independentcontrol.

Alternatively, if process 700 determines at block 720 that neither alevelling event nor a high-articulation event have precipitated the needfor a height change, the vehicle 100 may employ an average axle controlmethodology and proceed to block 730. Accordingly, adjustments are madeto the vehicle height on the basis of the average adjustment requiredmeasured at each wheel on a given axle. The average axle controlmethodology may be useful, for example, where a height change isinitiated by a newly selected ride mode or drive mode change, e.g., aselection of an off-road mode that increases vehicle ground clearance.In these situations, it is unlikely that a side-to-side variation in thevehicle 100 caused the height change. As such, the average axlemethodology generally prevents side-to-side adjustments of the vehicle100 where they are not expected to be necessary. Generally, equal cornerweights may be more easily achieved with the above average axle controladjustment, which may result in the best vehicle setup for dynamicbehavior. Accordingly, to the extent dynamic behavior is prioritizedwhen the driver requests a change, the average axle control methodologymay improve the ability of the vehicle to adjust to the correct heightmore quickly.

Turning now to FIGS. 8 and 9 , correction strategies for levellingcorrections to the vehicle 100 are illustrated and described in furtherdetail. Generally, vehicle 100 may seek to address suspension correctionconditions associated with the suspension system 101. Merely asexamples, changes in distribution of cargo, passengers, etc. in thevehicle 100 may cause the vehicle 100 to lean side to side, or to pitchtoward the rear of the vehicle 100 (“squat”) or front of the vehicle(“dive”). A suspension correction condition may include such a lean orpitch of the vehicle, which the vehicle 100 seeks to correct byadjusting pressure of one or more air springs 104. In the approachillustrated in FIG. 8 , an individual corner control (i.e., where eachair spring 104 is independently controlled to a target height) caninduce diagonally-asymmetric corner weights due to an over-constrainedsystem of vehicle 100. The over-constrained system, in this example,results from the vehicle 100 having four wheels and associated airsprings 104, as three points define a plane, adjustments made to one ofthe four air springs 104 may affect measured height and/or wheel weightsof one or more of the other air springs 104 and/or associated wheels. Anillustration of an over-constrained vehicle is provided in FIG. 15 . Inthe example, different wheel weights and pressures at the four wheellocations can result in an ongoing process where the vehicle makes aheight adjustment to a wheel, thereby altering the wheel weight ofanother wheel and creating a need for a height or pressure adjustment atthat wheel. In the correction strategy pictured in FIG. 8 , individualcorner control (i.e., independent axle control methodology) may beemployed for levelling corrections applied in response to, pitchcorrections, excessive, insufficient, or incomplete height corrections,and corner height corrections, while average axle control (i.e., wherethe correction determined for the two wheels of a single axle isaveraged, which each applied to the air springs 104 associated with thetwo wheels of the axle) is employed for execution of ride heightchanges. Employing the individual corner control in response to theindicated situations, however, can induce diagonally-asymmetric cornerweights. Increasing precision of the control, e.g., by reducing atolerance for error in ride height, may exacerbate the problem. In somecases, alignment capability is impacted.

Accordingly, in FIG. 9 an illustrative example is provided of acorrection that addresses the problems experienced in the strategyillustrated in FIG. 8 . Generally, in contrast to the approachillustrated in FIG. 8 , the approach illustrated in FIG. 9 employsindividual corner control only for incomplete corner height correctionsthat, e.g., which cannot be resolved with an initial attempt usingaverage axle control. More specifically, individual corner control isallowed only for subsequent attempts to correct height(s). Average axlecontrol is thus employed to effect ride height changes, pitchcorrections, excessive/insufficient height corrections, as well asinitial attempts at a corner height correction or a high-precisioncorner height corrections. In other words, height corrections caninitially be made using average axle control, with a subsequent attempt(e.g., if the first attempt using average axle control is not effectiveenough to reduce the error) being made using individual corner control.It should be noted that in some examples a relatively higher-precisioncontrol mode (i.e., with a relatively smaller tolerance for ride heighterror) is not employed during normal vehicle operation. Additionally,when the vehicle 100 determines it is present on flat surface or levelsof twist are relatively low, average axle control may be employed, whileindividual corner control may be employed. In this manner, asymmetryinduced by non-flat surface may be reduced or eliminated. The sameapproach may be employed for pitch corrections, i.e., average axlecontrol being employed when ground is flat or levels of twist arerelatively low, with individual corner control being employed whenground is relatively less flat (or levels of twist are above athreshold). When correcting for a relatively steep bank or grade (e.g.,a bank or grade above a predetermined value), individual corner controlmay also be imposed rather than average axle control. Furthermore, rollcorrections may in the example illustrated rely upon individual cornercontrol since the vehicle 100 leaning on one side may introduceasymmetry if average axle control is employed.

In should be noted that in some examples, axle height adjustment controlis performed independently on the two axles of a vehicle due to theunequal air pressures in each. For example, as illustrated in FIG. 16A,internal pressures of air spring(s) 104 of different axles may bedifferent to a greater degree than the weight distribution between afront axle and rear axle of the vehicle. More specifically, in theexample illustrated, the vehicle is shown having a front/rear weightdistribution that is nearly balanced, i.e., with very slightly more than50% of the vehicle's weight on the front axle, and very slightly lessthan 50% on the rear axle. Nevertheless, the air pressures of the frontaxle and rear axle are more significantly different. As a result, it maybe beneficial to control height adjustments of the front and rear axlesindependently. More specifically, as illustrated in an example process1600 in FIG. 16B, initially a vehicle may be in a standby mode at block1605. In response to a request for a raise in height of the vehicle 100,e.g., automatically by the vehicle or manually by a vehicle driver,process 1600 may proceed to block 1610. At block 1610, the vehicle mayinitially raise the rear axle until either the overall/requested heightadjustment is reached, or a permissible height difference between theaxles is reached. In cases where the permissible axle height differencelimit between the axles is reached as the rear axle is being raised,process 1600 may proceed to block 1615, where the front axle is raisedto an approximate equal height as the rear axle. Proceeding back toblock 1610, the rear axle may then be raised further. Process 1600 may,accordingly, proceed between blocks 1610 and 1615 to the extentnecessary to complete the height adjustment (i.e., process 1600 moves toblock 1615 if the permissible height difference between the axles isreached, and back to block 1610 if the front and rear heights areequalized without reaching the requested height). In this manner, thefront and rear axles may be adjusted incrementally in an alternatingfashion until the height adjustment is completed, with process 1600 thenproceeding back to block 1605. Accordingly, in some examples the vehicledynamics controller 102 may implement height changes at two differentaxles, i.e., the front/rear axles, within an axle height differencelimit. More specifically, a first height change is initiated at a firstone of the two axles, e.g., the rear axle, until the axle heightdifference limit is reached. Subsequently, a second height change may beinitiated at a second one of the two axles, e.g., the front axle, untilone of the height difference limit or an overall height change isreached. In cases where the second height change, e.g., to the frontaxle, is insufficient to achieve the requested height change, i.e., thesecond height change is initiated until the height different limit isreached, a third height change may be initiated, e.g., at the rear axle.Undesirable or extreme height differences between the axles may beminimized by employing this example alternating-axle, incrementalapproach. In an example, a permissible height difference between thefront/rear axles may be altered according to vehicle conditions. Forexample, a vehicle may employ a first permissible height difference(e.g., 20 millimeters) while the vehicle is being operated or driven,which is relatively smaller than another permissible height difference(e.g., 40 millimeters) used during other times when the adjustments areless likely to be noticed by vehicle passengers.

Turning now to FIGS. 10 and 11 , a problem arises at times in an airsuspension system where air pressures of the air springs 104, e.g., on asingle axle, are not necessarily equal due to different circuitimpedances. As illustrated in FIG. 10 , one approach exemplifiedincludes opening valves, e.g., of an air spring 104, to raise or loweran axle. After the axle is determined to be within a specified tolerancerange of the target height, the valves may be closed. In some cases,using the approach outlined in FIG. 10 may result in different internalpressures in the air springs 104 of the axle. Turning now to FIG. 11 ,in an example process 1100, one solution to the problem illustrated inFIG. 10 is to subsequently equalize pressure of the air springs 104 of agiven axle, i.e., after implementing a height change at the axle usingthe air springs 104 associated with opposite wheels (not shown) of theaxle. More specifically, process 1100 may begin at block 1105, where oneor more valves are opened to raise or lower an axle of vehicle 100.Proceeding to block 1110, the valves may be closed upon detection thatthe average axle height is within a target or specification. Proceedingto block 1115, with the compressor 106 off and an exhaust valve closed,valves of the associated air springs 104 at each corner of the axle maybe opened to allow equalization of the pressure in each of the airsprings 104 of the axle. Process 1100 may then terminate.

Turning now to FIG. 12 , an example control strategy 1200 for addressingover-corrections of an air suspension system of vehicle 100 isillustrated and described in further detail. More specifically, in somecases mild dynamic maneuvers of the vehicle 100 may induce the airsuspension system to make levelling corrections to the vehicle 100 thatmay not be necessary. In this example, a height control target of 5millimeters (mm) is employed, i.e., such that variations of greater than5 mm may induce levelling response by the vehicle dynamics module 102.Mild dynamic maneuvers may induce movements that exceed the controltarget, e.g., 5 mm, which could cause intervention by the vehicledynamics module 102 which are generally not desired. Attempts have beenmade to compensate based upon acceleration of the vehicle, e.g., alongthe vehicle longitudinal or lateral axis, however “false positives”where the vehicle dynamics module 102 interprets mild dynamic maneuversas requiring levelling correction may still occur. In a further effortto reduce the extent to which the levelling system may attempt tocorrect in these mild dynamic situations, applicable thresholds forintervention may be scaled based upon other factors, either asalternatives or in addition to scaling applied based upon accelerationsof the vehicle 100. In the example illustrated in FIG. 12 , thresholdsfor levelling interventions may be scaled based upon various suspensionoperating conditions such as roughness or flatness/twist.

In the example control 1200 illustrated in FIG. 12 , at block 1205suspension operating conditions may include steer angle of the vehicle100, longitudinal acceleration of the vehicle 100, lateral accelerationof the vehicle 100, bank of a surface being traversed by the vehicle100, and grade of the surface. These factors may be used to scalethresholds in combination with roughness and/or flatness/twist, whichmay be applied to scale thresholds at block 1210. Accordingly, in theexample illustrated in FIG. 12 , each of these suspension operatingconditions are used to change one or more settings associated with thesuspension system. While in this example settings may include thresholdsthat are scaled according to roughness, flatness/twist, lateralacceleration, longitudinal acceleration, steer angle, bank, and grade,any other factors may be relied upon that are convenient.

Generally, suspension operating conditions may be used to provide acalibratable relationship between surface conditions, e.g., roughnessand/or twist, and de-sensitization of height adjustments of the vehicle100 and/or suspension system 101. Additionally, desensitization may beused generally to correct for or prevent overcorrections of vehicleheight or adjustments as mentioned above. For example, if a single oneof the air springs 104 is out of range and a correction is made, in afour-wheeled vehicle this will necessarily cause a redistribution ofvehicle weight that will affect the other air springs 104. As a result,it is possible for the adjustments to one air spring 104 of thesuspension system 101 to create the need for an adjustment to another ofthe air spring 104. Accordingly, the vehicle 100 may detect theoccurrence of these repeated adjustments, and further adjustments may bede-sensitized (e.g., to increase acceptable tolerances/ranges for heightadjustment) in an effort to more quickly stop the vehicle or suspension“hunting” further adjustments.

In the example control 1200 illustrated in FIG. 12 , at block 1215 acount of adjustments made by the vehicle 100 may be used to track heightadjustments by the vehicle 100. As the number of height adjustments in aperiod of time go up, the control 1200 may increase tolerances, therebyreducing the degree to which the vehicle 100 seeks to make additionalheight changes. This adjustment count may thus be employed to preventpotential “hunting” by the vehicle 100, as described above. Theadjustment count may reset or be reduced upon the vehicle 100 coming toa stop or other changed condition indicating the vehicle 100 shoulddetermine whether further height adjustment(s) should be made. In thismanner, thresholds of the suspension system 101, e.g., a heightadjustment threshold, may be scaled in response to a detection of thevehicle 100 making too many adjustments to vehicle height within a givenperiod of time.

At block 1220, a context switch is employed to emphasize or ignoredynamic desensitization. More specifically, if it is known that heightsmeasurements are reliable while the vehicle 100 is in motion, then anassumption can be made that the height measurements are still reliablewhen the vehicle 100 comes to a stop, and as a result alldesensitization can be applied when the vehicle 100. On the other hand,if it is known that height measurements are not reliable while driving,the vehicle 100 may not be able to make adjustments. Accordingly, inthis example, the vehicle 100 may finish making adjustments when thevehicle 100 stops. For example, the vehicle stopped indicator of block1215 may cause desensitizations to be eliminated, and flatness is usedas the sole scaling factor with respect to thresholds.

Examples of scaling of thresholds as set forth above will now bediscussed in further detail. In the examples that follow, a heightadjustment tolerance may be approximately 7.5 millimeters (mm) whiledriving (i.e., when speed of the vehicle 100 is above zero), and may berelatively greater while vehicle 100 is stopped (e.g., 10 mm).Additionally, a greater tolerance yet may be applied while the vehicle100 has its brakes applied (due to binding of suspension components thatmay occur while applying brakes).

In a first example where roughness is used to scale a height adjustmentthreshold, an amount of roughness determined may be used to scale a gainassociated with the standard input tolerance (e.g., 10 mm when thevehicle 100 is stopped). The gain may be applied such that it isgradually phased in to increase tolerance minimally in response torelatively low roughness, and then rapidly increased as a higher degreeof roughness is detected. For example, as illustrated in Table 1 below,when roughness determined to be below 30 percent, zero gain is appliedsuch that the standard tolerance range of 10 mm is used. Increases ofroughness to 30 percent may increase minimally as reflected below, whileroughness above 50% causes an extremely large increase that effectivelyreduces or eliminates height adjustments by the vehicle 100.

TABLE 1 Roughness Roughness (%) Gain 0 0 30 0.1 (e.g., 11 mm instead of10 mm) 40 2.0 (e.g., 30 mm instead of 10 mm) 50 10.0 (e.g., 120 mminstead of 10 mm)

It should be noted that, by comparison, maximum travel of an air spring104 of vehicle 100 may be on the order of 120-150 millimeters in bothup/down directions. In one example, maximum travel from a nominalposition at standard height is such that the air spring 104 may allowwheel jounce upward by 150 mm, and wheel rebound downward from thenominal position by 120 mm. Accordingly, in the example set forth abovein Table 1, at higher levels of roughness adjustments almost entirelyphased out.

Gains associated with height adjustment thresholds may be scaled inresponse to other factors. For example, flatness or twist may be used asset forth in Table 2, below, to scale a height adjustment threshold.Again, gain may be applied such that it is gradually phased in toincrease tolerance minimally in response to relatively levels of twistor relatively flat surfaces, and then rapidly increased as higheramounts of twist is detected. In the example illustrated in Table 2below, when twist is determined to be below 20 millimeters, zero gain isapplied such that the standard tolerance range is used. Increases oftwist to 30 mm may increase gain minimally as reflected below, whiletwist above 100 mm causes an extremely large increase that effectivelyreduces or eliminates height adjustments by the vehicle 100.

TABLE 2 Twist/Flatness Twist (mm) Gain 0 0 20 0.1 (e.g., 11 mm insteadof 10 mm) 30 1.0 (e.g., 20 mm instead of 10 mm) 100 10.0 (e.g., 120 mminstead of 10 mm)

As another example of scaling height adjustment thresholds in responseto detected conditions, lateral acceleration may be used to reduce oreliminate interventions by vehicle 100 and/or suspension system 101during relatively high lateral acceleration. An example is set forth inTable 3, below, to scale a height adjustment threshold. Again, gain maybe applied such that it is gradually phased in to increase toleranceminimally in response to relatively low levels of lateral acceleration,and then rapidly increased as higher amounts of lateral acceleration aredetected. In the example illustrated in Table 3 below, when lateralacceleration is determined to be below 0.5 m/s′, zero gain is appliedsuch that the standard tolerance range is used. Increases of twist to 30mm may increase gain minimally as reflected below, while twist above 100mm causes an extremely large increase that effectively reduces oreliminates height adjustments by the vehicle 100.

TABLE 3 Lateral Acceleration Lateral Acceleration (m/s²) Gain 0.5 0 3.03.0 (e.g., 40 mm instead of 10 mm) 10 10.0 (e.g., 120 mm instead of 10mm)

It should be noted that in some examples, vehicle 100 may cut off heightadjustments when lateral acceleration of the vehicle 100 is above arelatively low threshold, e.g., below 3.0 m/s², to prevent a vehicleexiting a corner in a “rolled” condition as a result of the lateralacceleration.

Turning now to FIGS. 13A-13C, example strategies for reducing activityof a suspension levelling system, e.g., in vehicle 100, are illustratedand described in further detail. Generally, temperature, e.g., anambient temperature of the vehicle 100 or operating temperature of acomponents of the vehicle 100, may be detected as a suspension operatingcondition, and the controller, e.g., vehicle dynamics module 102, may beconfigured to reduce a suspension activity in response to a detection ofa temperature above a predetermined threshold. Further, in examplesbelow the vehicle dynamics module 102 and/or other controller of vehicle100 may be configured to change suspension activity between a pluralityof discrete suspension activity categories, with each of the discretesuspension activity categories including one or more suspensionoperating parameter adjustments.

In each of the three example strategies illustrated in FIGS. 13A, 13B,and 13C, respectively, certain functions of the vehicle 100,particularly of the air suspension, may be reduced in response to risingoperating temperatures of the compressor or other components (e.g., dueto rising ambient temperatures) and a suspension functionality level maybe changed in response. One example suspension functionality levelincludes a “full functionality” level of service (e.g., in which an aircompressor of the vehicle, e.g., compressor 106, is permitted to fill atank or reservoir anytime the vehicle is not in park, to raise thevehicle if the tank is depleted, and may enact speed-basedraising/lowering of the vehicle). The suspension functionality level maybe reduced from the full functionality level to other, more reducedlevels of suspension functionality or activity in response to detectedconditions. In some examples, reduced levels of suspension functionalitymay generally be used to prioritize driver requested height changes overautomatic height changes or corrections as the temperature of thehardware increases. These reductions to certain functions or activitiesmay prevent damage to components of the vehicle 100, e.g., aircompressor 106, due to operation in elevated temperatures, or topreserve electrical power of a battery pack of the vehicle 100. As shownin each of FIGS. 13A, 13B, and 13C, upon the vehicle 100 or suspensioncomponents reaching various temperature thresholds, the vehicle 100 maylimit functions of the vehicle 100 and/or air suspension system as notedin the “limited functionality” boxes, which provide other examples of asuspension functionality level. Accordingly, the discrete suspensionfunctionality levels may include at least the “limited” box, and in someexamples may include additional categories discussed further below. Uponreaching a subsequent temperature threshold above the first, additionalfunctions of the air suspension system may be limited, e.g., as noted inthe “limited functionality 2” box of FIG. 13C, or functions of the airsuspension system may be ceased entirely. In the “no functionality”suspension functionality level, the vehicle 100 may be operable butwithout the ability to modify ride height or other settings of the airsprings 104 and/or the suspension system.

Turning now to FIG. 14 , an example process 1400 for a vehiclecontroller or system, e.g., of vehicle 100, an air suspension system, orassociated control system, is illustrated. The example vehicle mayemploy determinations discussed above. Accordingly, process 1400 may beembodied on vehicle dynamics module 102, or any other controller ofvehicle 100 that is convenient.

Process 1400 may begin at block 1405, where generally, user heightrequests, user drive mode requests, and vehicle speed may be inputs toan arbitration of the height requests. A target height may be output.

At block 1408, process 1400 may use a measurement of twist or flatness,e.g., as described above, to determine whether a height change should berejected. More specifically, based upon determination of surfaceconditions at block 1420 as described below, process 1400 set a flag forprocess 1400 (e.g., at block 1425) to allow height changes if twist ofthe vehicle 100 is below a threshold amount. In this manner, heightchanges may be selectively rejected by the supervisory state machine1430 if the flag is not present at block 1425.

Proceeding to block 1410, the target height may be used to calculatecorner height targets, along with a bank and/or a grade. Accordingly,height changes may be made considering effects of a bank and/or a gradeof the vehicle may be traversing, e.g., as evidenced by vehicle lateralacceleration. As such, the influence of the bank and/or grade may beremoved. Target corner heights may be determined and output to a cornerheight error calculation. Process 1400 may then proceed to block 1415.

More particularly, at block 1415 target corner heights may be input,along with measured/actual corner heights, to a determination of cornerheight error. The corner height errors may be used in the roughnesscalculation, e.g., for a road or any other surface, as well as tocalculate a height correction.

More specifically, proceeding to block 1420, vehicle speed may be inputalong with corner height errors to determine surface conditions, e.g.,including a metric of roughness, e.g., as described above in FIG. 5 andthe example process 500, as well as a measure of flatness or twist ofthe vehicle 100 as described above. The roughness estimate may be aninput to the calculation of a height correction at block 1425, and asnoted above may be provided to block 1408 to determine whethersubsequent height changes may be restricted or prevented. If/when aheight correction is determined at block 1425, a supervisory statemachine at block 1430 may output a raise/lower request based upon theinput correction and the requested raise/lower received from the heightrequest arbitration. The raise/lower request is output to a hardwarecontrol state machine at block 1435, which outputs hardware commands toimplement the raising or lowering, e.g., by air pressure adjustments ofthe system as described herein. Process 1400 may then terminate.

In example systems such as that illustrated in FIG. 14 , ride heightchanges may be made based upon vehicle speeds and/or modes of operationof the vehicle/suspension system. Ride height adjustments may be madebased upon vehicle mode and/or speed, e.g., as illustrated and describedfurther below in FIGS. 17A-17G and 18-21 . Generally, various modes ofthe vehicle 100 may be used to emphasize energy efficiency of thevehicle, particularly where the vehicle is an electric vehicle whereelectrical power is desired to be conserved, or other desiredperformance/vehicle qualities. In some examples, vehicle drag may bereduced by lowering height at speed, thereby improving efficiency andrange of the vehicle. In the illustrated examples, a ride height of thevehicle may induce speed limits, e.g., such that a relatively high orrelatively low ride height or ground height may result in a speedlimiting of the vehicle to prevent, merely as one example, exceeding asafe speed when the vehicle has a relatively high center of gravity.Further, load leveling behavior may be based on corner heights in atarget window. Load leveling may use the example roughness metricsherein and adjust heights to stay in target windows, with additionallogic added for measured height errors, and while accounting for thevehicle being on different steep grades and banks.

In Table 1 below, a plurality of example ride heights are illustratedwith corresponding ground clearance and offset distance (from a nominalor standard ride height setting). The settings listed in Table 1 includea “max” setting, a “high” setting, a “standard” setting, a “low”setting, and a “lowest” setting. Generally, a user of vehicle 100 mayimplement the indicated ground clearances/settings in a given “mode” ofthe vehicle (e.g., a normal mode, off-road mode, etc.) and thenselecting one of the plurality of ride heights. It should be understoodthat while five different ride heights are illustrated, any number ofdifferent settings may be employed, and different ground clearances oroffsets may be employed in the plurality of ride heights.

TABLE 4 Ride Height Offsets Ride Height Offset from Standard (mm) Max+90 High +40 Standard Nominal (0) Low −35 Lowest −50The indicated ground clearances in Table 1 are measured with respect toa front subframe height, which may be a minimum ground clearance of thevehicle and may be relatively lower than a rear subframe height of thevehicle (e.g., to provide a desired stance of the vehicle where a rearof the vehicle is slightly higher than a front of the vehicle).

Referring now to FIGS. 17A-17H, implementation of the vehicle rideheights of Table 1 are described further in different vehicle modes andaccording to vehicle speed for the vehicle 100. The different modes maybe provided, e.g., in vehicle 100, facilitating selection of differentstrategies for ride height changes based upon speed. Generally, vehiclestability may be enhanced by a speed limit that is imposed by vehicle100 in response to a ride height. Further, speed limits the vehicle 100imposes may be communicated to the driver upon selection of a mode orheight, so that the driver has the opportunity to confirm or reconsiderthe height/mode request.

As noted above, vehicle modes and sub-modes may be selected andimplemented via a user-interface or display, e.g., as set forth above inconnection with FIGS. 3 and 4 . In the examples that follow, vehicle 100includes an all-purpose mode, a conserve mode, a sport mode (having a“launch” sub-mode), and an “off-road” mode (having sub-modes including“auto,” “rock-crawl,” “drift,” and “rally”). As will be describedfurther below, selection of a mode or sub-mode may result in theimposition of a vehicle height limit, e.g., such that the vehicle 100 isnot permitted to change ride height above a predetermined heightthreshold. The various modes and sub-modes may also provide speed limitsapplicable to certain ride heights, modes, or sub-modes, e.g., selectionof a relatively high ride height or vehicle ground height above apredetermined vehicle height threshold may cause a maximum speed limitto be imposed on the vehicle and/or communicated to the operator/driver.

A first example illustrated in FIG. 17A is directed to an “all-purpose”mode, in which ride height selections are restricted to thehigh/standard/low ride heights, e.g., as set forth in Table 1. Theall-purpose mode may generally be directed to normal on-road or lightoff-road applications, and thus may use settings such as ride height andother vehicle limits within nominal ranges.

As shown in FIG. 17A, with vehicle 100 in the all-purpose mode,automatic ride height adjustments may be implemented by vehicle 100 inresponse to changes in vehicle speed, as indicated by arrows 1700, 1702,and 1704. More specifically, when vehicle 100 is in the “high” rideheight setting, acceleration of the vehicle past 75 kilometers per hour(km/h) will cause the vehicle 100 to immediately lower ride height tothe “standard” ride height, as indicated by arrow 1700. Furtheracceleration of the vehicle past 82 km/h will cause the vehicle 100 tolower ride height to the “low” setting after remaining above 82 km/h for45 seconds, as indicated by arrow 1702. Further, upon decelerating to 62km/h, vehicle 100 will automatically raise ride height back to thestandard ride height, as indicated by arrow 1704. Height changes above135 km/h may also be prevented, including automatic corrections forlevelling as well as height changes requested by a driver/occupant ofthe vehicle 100. Generally, changes in ride height may be communicatedto a driver, e.g., by way of a display in an interior of the vehicle100. The various limitations on ride height changes illustrated in FIGS.17A-17G may be imposed by vehicle dynamics module 102 and/or othermodules or controllers associated with the vehicle 100. In an example,the vehicle dynamics module 102 imposes limitations relating to safety,e.g., to limit vehicle ride height selections to certain heights ormodes, or prevent all height changes above a vehicle speed threshold,while a separate controller or module of the vehicle 100 is responsiblefor imposing limitations relating to vehicle ride modes, e.g., to limitride height changes to be made in a manner consistent with a desireduser experience in each of the modes.

A second example mode illustrated in FIG. 17B is directed to a“conserve” mode, in which the vehicle 100 generally seeks to conservepower, e.g., when a traction battery of the vehicle has a relatively lowstate of charge. In the conserve mode, ride height selections may berestricted to the standard and lowest ride heights, e.g., as set forthin Table 1. The conserve mode may be convenient for reducing orminimizing consumption of electrical power by the vehicle 100. In theconserve mode of vehicle 100, ride height selections are limited betweenthe lowest and standard ride heights. Further, automatic ride heightadjustments may be implemented by vehicle 100 in response to changes invehicle speed, as indicated by arrows 1706 and 1708. More specifically,when vehicle 100 is in the standard ride height setting, acceleration ofthe vehicle past 50 km/h and remaining above that speed for at least one(1) second will cause the vehicle 100 to lower ride height to the lowestride height, as indicated by arrow 1706. As indicated by arrow 1708,upon decelerating to 45 km/h and remaining below that speed for at leastone (1) second, vehicle 100 will automatically raise ride height back tothe standard ride height. Height changes are also prevented aboverelatively higher speeds, e.g., above 135 km/h as illustrated in FIG.17B. The conserve mode may generally seek to reduce power consumption byminimizing wind resistance at higher speeds, while reducing the numberof raise/lower events through the reduced number of ride heightsettings.

A third example mode illustrated in FIG. 17C is directed to a “sport”mode, in which the vehicle may be relatively lowered, suspensioncomponents set to relatively stiffer settings, etc. Accordingly, rideheight selections in the sport mode may be generally restricted to lowerride heights to reduce height of a center of gravity of the vehicle 100.For example, the sport mode as illustrated in FIG. 17C restricts rideheights of vehicle 100 to the low and lowest ride heights as set forthin Table 1. Further, automatic ride height adjustments are disabled(i.e., changes between the low/lowest ride heights must be manuallyinput or requested by the vehicle driver), and ride height adjustmentsare blocked entirely above 135 km/h.

Turning now to FIG. 17D, an example fourth mode is directed to a “sportlaunch” mode/sub-mode. More particularly, the “launch” sub-mode may beinitiated in a menu of the user interfaces illustrated in FIGS. 3 and/or4 . In the launch sub-mode, vehicle settings such as ride height may beset to lowest/stiffest available settings to further reduce height ofthe vehicle's center of gravity, e.g., as may be useful for maximumacceleration from a standing stop. As illustrated in FIG. 17D, in thesport-launch mode the vehicle 100 remains in the lowest ride heightsetting, and all other ride heights are unavailable.

A fifth example mode illustrated in FIG. 17E is directed to an “off-roadauto/rock crawl” mode, which may be convenient when vehicle 100 istraversing off-road or obstacles at relatively low speeds. For example,“auto” or “rock crawl” sub-modes may be selected with the vehicle 100placed in the “off-road” mode, e.g., as described above in connectionswith FIGS. 3 and 4 . Available ride heights are limited to the high andmax ride heights. Automatic ride height settings are blocked. When thevehicle is in the max ride height, vehicle speed is limited to 40 km/h.Further requests from the driver to raise from the high ride height tothe max ride height are blocked above 20 km/h. Additionally, ride heightadjustments are blocked entirely above 135 km/h.

A sixth example mode illustrated in FIG. 17F is directed to “off-roaddrift” and “off-road rally” modes/sub-modes of the vehicle 100. Forexamples, “drift” and “rally” sub-modes may be selected with the vehiclein the “off-road” mode. In the off-road drift and off-road rallymodes/sub-modes, ride height selections may be restricted to thestandard and high ride heights, e.g., as set forth in Table 1. Further,automatic ride height adjustments are disabled, and ride heightadjustments are blocked entirely above 135 km/h.

A seventh example mode illustrated in FIG. 17G is directed to a “trailertowing mode” of the vehicle 100. All ride height adjustments aredisabled while the vehicle is moving (i.e., above 0 km/h), and manualride height adjustments selections are limited to the standard and lowride heights.

Referring now to FIG. 18 , a process 1800 for setting vehicle speedlimits in response to suspension system height inputs is illustrated anddescribed in further detail. Process 1800 may begin at block 1805, wherea vehicle speed limit is applied and communicated. For example, it maybe desirable to limit speed of the vehicle 100 from attaining higherspeeds when the vehicle is raised into a relatively high or maximumheight of the vehicle relative to a ground surface, e.g., a ride height.In the example vehicle modes set forth in FIGS. 17A-17G implementing theride heights of Table 1, the max ride height is available only in theoff-road auto/rock crawl mode. Further, as described above in connectionwith FIG. 17E, vehicle speed may be limited to 40 km/h upon selection ofthe max ride height within the off-road auto/rock crawl mode. One ormore of the ride heights may be above a predetermined vehicle heightthreshold applicable to the speed limit, such that when vehicle 100 isin a ride height that is above the limit, the speed limit(s) may beimposed and/or communicated to the operator/driver. Other maximum speedsmay be employed that are convenient and may be applicable to otherride/ground heights of the vehicle. As noted above, in some examples aspeed limit imposed by the vehicle 100, e.g., in response to a rideheight selection, may be communicated to the driver so that the driverhas the opportunity to confirm or reconsider the height/mode request.

Proceeding to block 1810 of process 1800, the speed limit of the vehicle100 may be initially maintained, e.g., in response to confirmation thatthe ride height selection causing the imposition of the speed limit,e.g., selection of the max ride height, has changed in response to thecommunication of the limit at block 1805 (e.g., the driver changes theirmind. Initially, at block 1810, the speed limit is maintained until thevehicle 100 confirms that the achieved height is less than the heightselection that caused the speed limit to be imposed. Accordingly,vehicle 100 may monitor ride height selections and maintain the speedlimit as long as the max ride height is requested and until it isconfirmed that the vehicle has not reached the max ride height. Inresponse to a detection that the ride height achieved by the vehicle isless than the max ride height (e.g., in response to a driver input), thevehicle 100 may remove the speed limit imposed at block 1815.

Turning now to FIGS. 19 and 20 , example processes for providing an“ease of entry” function in a vehicle, e.g., vehicle 100, areillustrated and described in further detail. Vehicle 100 may have anease of entry feature or mode that may be disabled by default in vehicle100, but which may be selected by a user/driver. Generally, the ease ofentry function may facilitate a lowering of the vehicle to enhance easeof entry for occupants to the vehicle. One example process 1900 isillustrated in FIG. 19 . Upon a detection that the vehicle 100 is inpark, process 1900 proceeds to block 1905. Generally, at block 1905process 1900 may change a ride height setting to a lowest available rideheight. In the example illustrated, block 1905 comprises a first block1905 a and a second block 1905 b. At block 1905 a, a target lowestheight is set for the vehicle 100. In an example, at block 1905 avehicle 100 may begin lowering to the target lowest height, e.g., thelowest ride height as set forth in Table 1. Proceeding to block 1905 b,upon detection of a vehicle door being opened, process 1900 may raisethe target height to the next highest ride height in real time. Forexample, if the vehicle is in between the “lowest” and “low” rideheights while lowering, the vehicle 100 may raise to the “low” rideheight (rather than continuing to lower to the “low” height) when thedetermination is made that the door is open. Accordingly, to the extentthe vehicle 100 has not reached the lowest ride height setting at thetime the door is opened, process 1900 generally avoids the doorcontacting an obstacle (which might otherwise result if the vehicle 100were to continue to lower as the door opened). Process 1900 may thenterminate. Turning now to FIG. 20 , another example process 2000associated with an ease of entry feature for vehicle 100 is illustratedand described in further detail. Generally, in process 2000 a previouslyselected target height may be implemented in response to a determinationthat the vehicle 100 is not in Park or otherwise prepared for driving.Accordingly, the vehicle 100 may be raised to a desired ride height froma lowered position, e.g., into which the vehicle 100 was previouslymoved to facilitate egress from the vehicle 100. In the illustratedexample, at block 2005 a previously selected height is targeted inresponse to the vehicle 100 being shifted from park. The vehicle 100 maycontinue being raised until the target ride height is reached, or it isotherwise no longer necessary to continue raising the vehicle 100 (e.g.,the vehicle mode or selected ride height is lowered, the vehicle ispowered down, etc.). Process 2000 may then terminate.

Referring now to FIG. 21 , an example process 2100 is illustrated anddescribed in further detail which implements a load levelling behaviorfor vehicle 100. In the example process 2100, roughness may generallyinfluence changes in ride height of the vehicle 100. More specifically,in the illustrated example an evaluation of a surface upon which thevehicle is traveling, e.g., a road surface, ground surface, trail, etc.,may be used to determine whether/when to implement vehicle heightchanges.

Process 2100 may begin at block 2105, in which a standby condition maybe used while vehicle 100 or components thereof monitor target cornerheights of the vehicle 100. For example, while travelling along a givensurface, process 2100 may monitor one or more corner heights of vehicle100, e.g., to determine whether the corner height(s) are within anapplicable range. When vehicle 100 detects that the corner height(s) arenot within the target window, process 2100 may proceed to block 2110.

At block 2110, process 2100 may evaluate a ground surface, e.g., of aroad, trail, or other surface being traversed by the vehicle 100. Forexample, process 2100 may determine a roughness, e.g., as describedabove in FIG. 5 . Block 2110 may categorize the result as being above orbelow a threshold to determine whether the surface being traversed is“smooth” or “rough.” Where it is determined at block 2110 that theroughness is “smooth,” process 2100 may proceed to block 2115.

At block 2115, process 2100 may initiate an adjustment of the cornerheight(s) initially determined to be outside the applicable targetwindow.

Alternatively, where it is determined at block 2110 that the roughnessis rough, process 2100 may proceed to block 2105 to standby. In thismanner, process 2100 may prevent vehicle 100 from attempting to levelthe vehicle while traversing relatively rough surfaces (or the vehicleis on a non-level surface, etc. as described above regarding FIG. 5 ).

It should be noted that process 2100 may proceed from block 2105 toblock 2115 in response to a detection that a height target has changed,e.g., vehicle 100 has initiated an automatic change in ride height, or adriver/user of vehicle 100 has manually requested a ride height change.Process 2100 may therefore proceed to adjust corner height(s) of thevehicle 100. Upon confirmation that the corner height(s) of the vehicleare each within their applicable target window(s), process 2100 mayproceed back to block 2105.

Turning now to FIG. 22 , an example process 2200 for implementing heightchanges in a vehicle, e.g., vehicle 100, is illustrated and described infurther detail. Generally, process 2200 may facilitate changes in rideheight based upon different control parameters. The use of differentcontrol parameters may be particularly beneficial in the context of avehicle with an air suspension system such as vehicle 100, however mayalso be used in the context of other suspension systems.

Generally, during nominal operating conditions the vehicle 100 and/orsuspension system 101 may close a control loop around a target movementof the suspension, e.g., displacement of one or more of the air springs104. At other times, however, control of ride height changes based ontarget movement or displacement may be difficult. For example, ifvehicle 100 is positioned on an uneven surface, rocks, or the like suchthat one wheel is relatively unweighted or “hanging” off the ground,additions/subtractions of air to/from the air spring 104 of theunweighted wheel may not result in a detectable displacement of the airspring 104. Accordingly, the vehicle 100 may be unable to determinewhether an appropriate adjustment to the air spring 104 has been madebased upon displacement/position of the air spring 104, and controllinga ride height change at such time using displacement/position as acontrol parameter may be difficult.

In view of this shortcoming of displacement/movement-based control, theexample process 2200 and/or vehicle 100 may control suspensionadjustments based upon a different parameter at times when adisplacement control criteria is not met, e.g., displacement control isnot feasible or may be ineffective. In other words, a displacementcontrol criteria may be defined to determine whether/whendisplacement/position may be used as a control parameter.

When process 2200 determines that displacement/position may not beeffective under the displacement control criteria, the vehicle 100 maycontrol additions/subtractions of air with respect to air springs 104based upon a different control parameter than displacement or position.For example, process 2200 may use air mass instead of displacement as acontrol parameter. In this example, the vehicle 100 may determine, basedupon a height change request, a target air mass of one or more (and insome examples all) of the air springs 104. The vehicle 100 may determinea target air mass based upon measurements of temperature of the airsprings 104, reservoir, or other suspension component. The vehicle 100may also determine a target air mass based upon a measured displacementof the air spring(s) 104. Based upon a known amount of air mass in theair spring 104, the vehicle 100 may then add/subtract an amount of airto/from the air spring 104 to achieve the target air mass of the airspring 104. As the air mass associated with air spring 104 may be moreeasily measured or detected than displacement/position when, forexample, the wheel of the air spring 104 is unloaded or substantiallyso, a control loop based upon air mass may be more effective toimplement a change in ride height change than one based ondisplacement/position. As a result, even during conditions when theadjustments to the air spring 104 may not result in a measurablemovement of the air spring 104 displacement (e.g., due to the suspensionof a wheel being fully extended or relatively unweighted), anappropriate adjustment may nevertheless be made to effect the change inride height.

Process 2200 may begin at block 2205, where a height change request fora vehicle suspension is received. Process 2200 may then proceed to block2210.

At block 2210, a height control method for implementing the heightchange may be selected in response to the height change request. In someexamples, a plurality of height controls may be available. One exampleheight control is displacement control, in which air is added to orremoved from one or more air springs of the vehicle suspension based ona target displacement of the one or more air springs. Another exampleheight control is an air mass control, in which air is added to orremoved from the one or more air springs of the vehicle suspension basedon a target air mass change of the one or more air springs.

As noted above, air mass control may be advantageous during certainconditions, such as when displacement control may be likely to beineffective. In an example, vehicle 100 and/or process 2200 may selectdifferent controls, e.g., displacement control or air mass control,based upon conditions. More specifically, vehicle 100 may considerconditions that may indicate a likelihood of displacement control to beeffective for implementing height change request. As noted above,displacement control may be likely to be ineffective when one or morewheels/air springs 104 are relatively unweighted, e.g., due tounevenness of a surface, rocks, etc. causing the wheel to be “hanging”from the vehicle.

The vehicle 100 and/or process 2200 may consider various factors thatmay indicate conditions where displacement control is likely to beineffective or otherwise may present challenges. In at least someexamples, the vehicle 100 may consider displacement of one or more ofthe springs of the vehicle 100 when selecting a control for implementingheight changes. As will be elaborated further below, displacement may beused to determine whether a spring of the suspension, e.g., air spring104, is unlikely to be able to control ride height changes usingdisplacement/position of the spring as a control parameter. Thedisplacement of the air spring 104 may be used to evaluate adisplacement control criteria, and a control parameter/variable forimplementing the ride height change may be selected based upon thedisplacement control criteria. In examples that follow, variousdisplacement control criteria may be defined to evaluate conditions todetermine whether displacement may be used as a control parameter forimplementing a ride height change.

In one example, displacement of a spring, e.g., air spring 104, may beevaluated to determine whether a displacement control criteria is metenabling usage of displacement as a control parameter. Generally, when awheel or air spring 104 of vehicle 100 is relatively unweighted adisplacement of the relatively unweighted air spring 104 may besubstantially different in comparison to at least one other of the airsprings 104 of the vehicle 100. For example, vehicle 100 may bepositioned on an uneven surface such that three wheels (and associatedair springs 104) are supporting the weight of the vehicle 100, with thefourth wheel hanging in space such that air spring 104 is extendedfurther in comparison to the other air springs 104, or even fullyextended. In this case, the displacement of the air spring 104 of thehanging wheel will be substantially greater than that of the other threeair springs 104. Similarly, a displacement of a single one of the airsprings 104 may also indicate a relative displacement with respect toother air springs 104 of the vehicle, which may indicate thatdisplacement control may not be feasible, and/or that air mass controlwould be beneficial. For example, if one of the air springs 104 is at amaximum displacement (i.e., wheel is fully extended from vehicle), thismay generally indicate that other air springs 104 of the vehicle are notfully extended. In other words, to an extent that one wheel of thevehicle is fully extended or substantially so while the vehicle isstationary or at a relatively low speed, this can also indicate that theassociated air spring 104 is relatively unweighted. As such, the otherwheels/air springs 104 of the vehicle necessarily are carrying a largerproportion of vehicle weight, and are relatively less extended.Accordingly, in some examples a displacement control criteria indicativeof selecting air mass control may be determined from a displacement of asingle one of the wheels or air springs 104. For example, displacementof one or more of the air springs 104 may be compared with adisplacement threshold (e.g., based upon a maximum or minimumdisplacement, or other appropriate threshold) to determine whether thedisplacement control criteria is met.

A displacement control criteria indicating that an air mass control maybe beneficial may also be indicated by a level of twist of the vehicle.As noted above, twist may be defined as a difference between relativedisplacement differences of one axle of vehicle 100 in comparison to adifferent axle. If such a comparison of displacements of the air springs104 indicates a level of twist above a twist threshold, this may alsoindicate relative unweighting of at least one wheel/air spring 104, andas such an air mass control for ride height changes may be beneficial.

In another example, a displacement control criteria indicating that airmass control may be beneficial may be determined from a load of one ormore of the air springs 104. The air springs 104 may include a load cellto measure load of the air spring 104 directly. Alternatively, vehicledynamics module 102 or other controller of the vehicle 100 may beconfigured to determine load based upon measured displacement of the airspring 104 and any other measurements, e.g., vehicle weight, pitch/roll,air mass, and/or temperature. In an example, if an air spring 104 isbelow a load threshold, e.g., a minimum load, or is unweighted, thiswould also indicate that the air spring 104 is fully extended orsubstantially so, and that other air springs 104/wheels of the vehicle100 are carrying a relatively larger share of vehicle weight (andtherefor are relatively less extended).

In a further example, a plurality of the foregoing factors, i.e., load,displacement, and twist, are considered together or in any subset thatis convenient as part of a displacement control criteria.

It should also be noted that, to an extent displacement control is notfeasible or may be ineffective, this may also indicate that anindependent/individual control methodology with respect to the airsprings 104 of the vehicle may also be beneficial, at least incomparison to an average axle height methodology. As noted above, duringsome operating conditions of vehicle 100, it may be desirable to controlheight/changes of the vehicle 100 based upon an average of measurementsbetween both air springs 104 of the vehicle 100. However, as also notedabove, where one wheel of an axle is relatively unweighted or relativelydisplaced compared to the other wheel of the same axle an individual orindependent axle height control methodology (i.e., where control targetsare implemented independently at each air spring 104 of a single axle ofthe vehicle 100). Accordingly, in at least some example approaches, aselection of air mass control at block 2210 also results in a selectionof independent axle height control.

Process 2200 may then proceed to block 2215. At block 2215, anadjustment to one or more springs of vehicle 100 may be initiated basedupon the control selected at block 2210. Where a displacement control isselected at block 2210, a target displacement or position of one or moreof the air springs 104 of vehicle 100 may be set, and adjustments to theair springs 104 (e.g., by adding/subtracting air from the air spring(s)104) may be made in an effort to achieve the target displacement.

On the other hand, where air mass control has been selected at block2210, at block 2215 an air mass target may be set. A target air mass maybe identified by vehicle 100, e.g., by vehicle dynamics module 102 basedupon measurements associated with the suspension system 101. The vehicledynamics module 102 may determine a target air mass change, i.e., aquantity of air to be added or subtracted from one or more air spring104. The vehicle dynamics module 102 may also determine an action toimplement the target air mass change based on one or more of adisplacement of the air spring or a temperature of an air reservoir or asuspension component. Accordingly, the vehicle 100 may set a target airmass based upon, merely as examples, temperature (e.g., to an extenttemperature affects expansion/contraction of air within the air spring104) or position of suspension components (e.g., air spring 104).

After the adjustment of block 2215 is completed, process 2200 mayproceed to block 2220. At block 2220, process 2200 may query whether thecontrol target set at block 2215 has been achieved. In an example, thedetermined control target, e.g., a displacement target or air masstarget, is compared with actual measurements. Where process 2200determines that the target has been achieved, or is within apredetermined acceptable range, process 2200 may terminate.Alternatively, if the target has not been achieved, process 2200 mayproceed back to block 2210, where process 2200 may again determine anappropriate control parameter and proceed to adjust components of theair suspension 101 of the vehicle 100. To an extent a first type ofcontrol parameter, e.g., displacement, is selected and determined to beineffective, process 2200 may selects a different control parameter,e.g., air mass, in subsequent attempts.

The systems and processes discussed above are intended to beillustrative and not limiting. One skilled in the art would appreciatethat the actions of the processes discussed herein may be omitted,modified, combined, and/or rearranged, and any additional actions may beperformed without departing from the scope of the invention. Moregenerally, the above disclosure is meant to be exemplary and notlimiting. Accordingly, the bounds of the claimed invention(s) should bedetermined from the claims and is not limited by the present disclosure.Furthermore, it should be noted that the features and limitationsdescribed in any one embodiment may be applied to any other embodimentherein, and flowcharts or examples relating to one embodiment may becombined with any other embodiment in a suitable manner, done indifferent orders, or done in parallel. In addition, the systems andmethods described herein may be performed in real time. It should alsobe noted that the systems and/or methods described above may be appliedto, or used in accordance with, other systems and/or methods.

While some portions of this disclosure may refer to “convention” orexamples, any such reference is merely to provide context to the instantdisclosure and does not form any admission as to what constitutes thestate of the art.

The foregoing description includes exemplary embodiments in accordancewith the present disclosure. These examples are provided for purposes ofillustration only, and not for purposes of limitation. It will beunderstood that the present disclosure may be implemented in formsdifferent from those explicitly described and depicted herein and thatvarious modifications, optimizations, and variations may be implementedby a person of ordinary skill in the present art, consistent with thefollowing claims.

What is claimed is:
 1. A suspension system for a vehicle, comprising: acontroller configured to: determine the vehicle is in a serviceenvironment; and set a height precision mode for the suspension systembased on the determination the vehicle is in the service environment. 2.The suspension system of claim 1, wherein the height precision mode isselected from a plurality of height modes having different correspondingcontrol tolerances, wherein the controller is configured to identify anoptimal one of the plurality of height modes based on the determinationthe vehicle is in the service environment, and to modify the suspensionsystem to be in the determined height precision mode; wherein thecontroller is further configured to disable an average axle controlleveling of the vehicle based on the determination the vehicle is in theservice environment.
 3. The suspension system of claim 1, wherein thecontroller is further configured to determine the vehicle is outside ofthe service environment to set a height axle control mode, wherein theheight axle control mode includes at least an average axle controlmethodology, wherein a height adjustment of the suspension is based uponan average of two vehicle heights determined at a single axle of thevehicle.
 4. The suspension system of claim 1, wherein the controller isfurther configured to determine the vehicle is outside of the serviceenvironment to set a height axle control mode, wherein the height axlecontrol mode further includes an independent axle control methodology,wherein first and second height adjustments are independentlyimplemented at a first wheel of an axle of the vehicle and a secondwheel of the axle.
 5. The suspension system of claim 4, wherein thecontroller is configured to implement the independent axle controlmethodology in response to one of: detecting a height error; ordetecting an incomplete height correction.
 6. A suspension system for avehicle, comprising: a controller configured to: detect a suspensionoperating condition of the vehicle; and change a setting associated withthe suspension system based on the suspension operating condition. 7.The suspension system of claim 6, wherein the suspension operatingcondition includes one of a ground surface angle, a vehicle steeringangle, a vehicle speed, a suspension correction condition, or an ambienttemperature.
 8. The suspension system of claim 6, wherein the settingassociated with the suspension system includes one of a height changelimit, a vehicle speed limit associated with a ride height, a heightchange precision, an axle height adjustment independence level, a heightadjustment threshold, or a suspension functionality level.
 9. Thesuspension system of claim 6, wherein the suspension operating conditioncomprises a vehicle ground height, wherein the setting associated withthe suspension system comprises a vehicle speed limit, and wherein thecontroller is configured to implement the vehicle speed limit inresponse to the vehicle ground height being above a predeterminedvehicle height threshold.
 10. The suspension system of claim 6, whereinthe suspension operating condition comprises vehicle speed, wherein thesetting associated with the suspension system comprises a vehicle heightlimit, and wherein the controller is configured to implement the vehicleheight limit in response to the vehicle speed being above apredetermined vehicle speed threshold.
 11. The suspension system ofclaim 6, wherein the suspension operating condition is one of anindividual wheel articulation above a predetermined relativearticulation threshold, an automatic levelling event, a drive modechange, or an operating environment of the vehicle, and wherein thesetting comprises an axle height control methodology.
 12. The suspensionsystem of claim 11, wherein the axle height control methodology includesat least an average axle control methodology, wherein a heightadjustment of the suspension is based upon an average of two vehicleheights determined at a single axle of the vehicle.
 13. The suspensionsystem of claim 12, wherein the axle height control methodology furtherincludes an independent axle control methodology, wherein first andsecond height adjustments are independently implemented at a first wheelof an axle of the vehicle and a second wheel of the axle.
 14. Thesuspension system of claim 13, wherein the controller is configured toimplement the independent axle control methodology in response to oneof: detecting the operating environment of the vehicle is one of amanufacturing environment or a service environment; detecting a heighterror; or detecting an incomplete height correction.
 15. The suspensionsystem of claim 6, wherein the controller is configured to implementheight changes at two different axles within an axle height differencelimit, such that a first height change is initiated at a first one ofthe two axles until the axle height difference limit is reached, and asecond height change is initiated at a second one of the two axles untilone of the height difference limit or an overall height change isreached, wherein the second height change is initiated until the heightdifferent limit is reached, wherein the controller implements a thirdheight change at the first one of the two axles.
 16. The suspensionsystem of claim 6, wherein the suspension operating condition includesan ambient temperature of the vehicle, wherein the controller isconfigured to reduce a suspension activity in response to a firsttemperature detected above a predetermined threshold.
 17. The suspensionsystem of claim 6, wherein the controller is configured to change asuspension activity between a plurality of discrete suspension activitycategories, each of the discrete suspension activity categoriesincluding one or more suspension operating parameter adjustments. 18.The suspension system of claim 6, wherein the controller is configuredto equalize an air pressure of a plurality of air springs of a singleaxle after implementing a height change at the single axle, theplurality of air springs associated with opposite wheels of the singleaxle.
 19. The suspension system of claim 6, wherein the controller isconfigured to change one or more heights of the vehicle by changing anamount of air contained by one or more air springs of the vehicle.
 20. Amethod, comprising: detecting, using a controller, a suspensionoperating condition of a suspension system of a vehicle; and changing,using the controller, a setting associated with the suspension systembased upon the suspension operating condition.